The Muscle Phenotyping and Imagine Core is designed to enable muscle and non-muscle researchers alike to access a variety of assessment tools for the study of muscle phenotypes. The Core will be useful in 3 main ways. First, the Core will provide a means for investigators to test lead therapeutic compounds in mice to evaluate their effect on muscle pathology. Drugs that delay the onset of disease or reduce muscle pathology will be identified through the small molecule high-throughput screen (Core B) or can be investigator initiated. For these assessments, both traditional (histology, muscle function tests) and non-traditional (optical imaging, MRI) methods will be available for researchers to utilize on a fee for service basis. Second, because most muscular dystrophies involve changes in the dystrophin-glycoprotein complex, biochemical assessments of muscular dystrophy-related proteins will be an additional service offered by this core. Finally, as more and more researchers are making use of transgenic mouse technology, it has become necessary for these individuals to explore muscle phenotypes in their novel knock out and transgenic animals. Since these researchers lack the necessary experience to assess muscle tissue, this Core will provide access to resources, expertise and training necessary to allow them to explore muscle morphology and function in a manner that would not otherwise be available to them. The Aims of the Core are: Aim 1: To enable researchers the opportunity, resources and training to evaluate muscle phenotypes in transgenic mice; Aim 2: To enable researchers the opportunity, resources and training to evaluate the efficacy of pharmacological compounds on muscular dystrophy pathogenesis, using quantitative functional and histological outcome measures as well as state-of-the art imaging technologies; Aim 3: To enable researchers the opportunity, resources and training to evaluate biochemical outcomes following treatments with pharmacological compounds.